1. Technical Field
The present invention related to a sheet manufacturing apparatus and a method for manufacturing sheet.
2. Related Art
In used paper discharged from offices, used paper describing confidential matters is included. Therefore, from the viewpoint of security protection, it is also desired that such used paper can be processed in their offices. In small offices, a wet-type sheet manufacturing apparatus, which uses a large amount of water, cannot be suitably used, and therefore a dry-type sheet manufacturing apparatus simplified in structure has been proposed (see, for example, Japanese Unexamined Laid-open Patent Application No. 2012-144819).
In the aforementioned sheet manufacturing apparatus, a component such as ink particles, etc. included in the fibers is removed by defibrating a used paper. So-called deinking process is performed. However, by the deinking process, it is difficult to totally remove the ink particles, etc. in, for example, the used paper having much amount of prints such as a graph, a picture, etc. printed by the electrographic, or the used paper in which the fiber itself is dyed and printed by the dying ink such as inkjet method, etc. so that there is a problem that a sheet in which the whiteness is low is formed. On the other hand, a stock material of a sheet is not only the printed used paper but also a pulp sheet or a non-printed sheet. Therefore, even when the used paper having much amount of prints is used as a stock material, a certain amount of whiteness enhancer is applied so as to become a sheet having high whiteness. However, there is a problem that when the used paper having low amount of prints or a pulp sheet is used as a stock material, the amount of whiteness enhancer use is exceeded.